IgA nephropathy and thin basement membrane disease in association with Crohn disease.

There have been a wide variety of reported renal parenchymal diseases associated with inflammatory bowel disease, ranging from interstitial nephritis to amyloidosis to immune complex glomerulonephritis. Two pediatric cases of renal parenchymal pathology in association with Crohn disease are presented. The first is an 11-year-old child who presented with recurrent bouts of gross hematuria, biopsy-proven IgA nephropathy, and later developed Crohn disease 4 years after the initial presentation. Her renal function is normal with persistent isolated microscopic hematuria. The second case is that of a 9-year-old male who presented with the classic gastrointestinal manifestations of Crohn disease, later developed hematuria and proteinuria, and was found on a renal biopsy to have thin basement membrane disease. There have been several reported cases of IgA nephropathy associated with inflammatory bowel disease; but to our knowledge, this is the first case of thin basement membrane disease occurring in conjunction with Crohn disease. Discussion focuses on the relationship of IgA nephropathy with inflammatory bowel disease with additional comments on thin basement membrane disease.